Convergence is the coordinated movement and focus of our two eyes inward on close objects, including phones, tablets, computers, and books. Convergence is one of many vital visual skills learned during our early years, as we begin to make sense of the world and how to use our eyes to take it all in. Think of how much convergence a person must do throughout each day!
Convergence Insufficiency is a common problem with the development of these skills. When convergence is insufficient, it means that the eyes do not come together closely enough when looking at a near object, so the eyes are essentially looking "past" the target focal point.
Convergence Insufficiency affects approximately 5% of children in the United States, and may have a serious impact on an individual's performance in school, choice of jobs, and quality of life.
When we are not able to converge our eyes easily and accurately, problems may develop, such as:
It is not unusual for a person with convergence insufficiency to cover or close one eye while reading to relieve the blurring or double vision. Symptoms will be worsened by illness, lack of sleep, anxiety, and/or prolonged close work.
Many people who would test as having convergence insufficiency [if tested] may not complain of double vision or the other symptoms listed above because vision in one eye has shut down. In other words, even though both eyes are open and are healthy and capable of sight, the person's brain ignores one eye to avoid double vision. This is a neurologically active process called suppression.
Convergence Insufficiency disorder has often gone undetected because testing is not included in pediatrician's eye tests, school screenings, basic eye exams. A person can pass the 20/20 eye chart test and still have convergence insufficiency.
If untreated, in some cases, convergence insufficiency can lead to an outward eye turn that comes and goes. This is called intermittent exotropia.
Eye coordination problems like convergence insufficiency generally cannot be improved with eye glasses or surgery. A program of vision therapy may be needed to improve eye coordination abilities, reduce symptoms, and alleviate discomfort when doing close work.
The American Optometric Association and the 2008 Convergence Insufficiency Treatment Trial clearly support the superiority of office-based vision therapy, supplemented by at-home vision therapy, for treatment of convergence insufficiency.
"There are no visible signs of this condition; it can only be detected and diagnosed during a comprehensive eye examination," said principal CITT Study investigator Mitchell Scheiman, O.D., FCOVD, of Pennsylvania College of Optometry at Salus University near Philadelphia, PA. "However, as this study shows, once diagnosed, CI can be successfully treated with office-based vision therapy by a trained therapist along with at-home reinforcement."
In general, 12-24 in-office vision therapy sessions are recommended to treat convergence insufficiency. This will vary based on compliance, the degree of convergence insufficiency (and other binocular disorders if present), age, and if there are any coexisting developmental disorders. With respect to regression following vision therapy, the Convergence Insufficiency Treatment Trial Group has found that 87.5% of children aged 9-13 were still considered either improved or successful one year after receiving treatment. Regression after vision therapy can occur after severe infection and/or traumatic brain injury.
The Convergence Insufficiency Treatment Trial found that for adults aged 19-30, 50% receiving office-based vision therapy for CI were either “improved” or “cured” after 12 weeks based on symptoms and clinical measures. It is possible that with more sessions there would have been a larger number of adults with CI benefiting from vision therapy. Also, investigators noted that the adults in this study improved the same amount clinically as children in another study suggesting that adults rate their symptomology differently than children.
In recent years, several randomized clinical trials have been published comparing the effectiveness of treatments for CI in children and adults. These studies have used both symptoms and clinical signs as outcome measurements. The results of these studies demonstrate that office-based vision therapy with home reinforcement is the most effective treatment for CI in children and adults. (4,5,6)
The Convergence Insufficiency Treatment Trial (CITT) is a prospective, masked, placebo-controlled, multi-center clinical trial in which 208 subjects between the ages of 9 to < 18 years were randomly assigned to: 1) Home-based Pencil Push-Up Therapy, 2) Home-based Pencil Push-ups with Computer Vision Therapy/Orthoptics, 3) Office-based Vision Therapy/Orthoptics, or 4) Placebo Office-based Vision Therapy/Orthoptics.
The primary outcome measure is a measure of symptoms using a 15-item survey, the CI Symptom Survey. Secondary outcome measures are two common clinical tests of the eyes' ability to converge when performing close work. Patients were tested at the eligibility examination, and by masked examiners after 4, 8 and 12 weeks of treatment have been completed during the 12-week treatment phase.
Per the Convergence Insufficiency Treatment Trial (CITT), 80% of patients treated with vision therapy reported both a subjective decrease in symptoms and improved objective measure of fusion at near compared to 8.3% in the placebo group and 0% in the pencil push-up group.
A larger follow-up study by the CITT investigator group reported symptom improvement and objective measures of fusion to be most improved in children treated with a combination of office-based therapy with home reinforcement compared to office-based therapy alone, home-based therapy alone, or placebo treatment.
You may also be interested in these blog posts:
Scheiman M, Mitchell GL, Cotter S, et al. In Reply: Convergence Insufficiency Randomized Clinical Trial. Arch Ophthalmol. 2005;123:1760–1761.
Convergence Insufficiency Treatment Trial (CITT) Study Group. Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol. 2008;126:1336–1349.
Scheiman M, Cotter S, Rouse M, et al. Convergence Insufficiency Treatment Trial Study Group (2005). Randomised clinical trial of the effectiveness of base-in prism reading glasses versus placebo reading glasses for symptomatic convergence insufficiency in children.British Journal of Ophthalmology, 89 (10), 1318–1323.
Scheiman M, Mitchell GL, Cotter S, Kulp MT, Cooper J, Rouse M, Borsting E, London R, Wensveen J. A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults. Optom Vis Sci. 2005;82:583–595.